(eg. 13-0-13), as an example. These numbers stand for percentages. The first is (N) Nitrogen, Second is (P) Phosphate, Third is (K) Potash.
Nitrogen dissolves very quickly and can run off if ground is saturated with continous down pours of heavy rain.
The second number is phosphate. Phosphate tends to stay in the soil instead of running off.
The third number potash moves quickly like nitrogen, dissolves rapidly and moves fast to the root zone.
All purpose fertlizer works great, but after several years the phospate tends to build up which could be harmful to plants. It is recommended to test your soil to decide the percentages you need in the fertilizer that you buy if you have already been using all purpose fertilzer for several years.
